The present invention relates to the derivatives of 2,2-dimethyl-5-substituted phenoxy-pentanoic acid, and in particular to the 3-substituted derivatives of 2,2-dimethyl-5-substituted phenoxy-pentanoic acid and the process of preparing the same and the intermidates thereof.
Substituted phenoxyalkanoic acids, for example the compounds represented by formulas (V) and (Va) below have been shown to be effective as hypolipoproteinemic agents. ##STR1##
According to U.S. Pat. No. 3,674,836 issued to Paul L. Creger and U.S. Pat. No. 3,707,566 issued to Paul L. Creger et al and J. Med. Chem. 31, 1207(1988), compound (V) may be prepared by the following scheme A. ##STR2##
According to U.S. Pat. No. 4,665,226 issued to Francis R. Kearney, and J. Med. Chem. 30, 1816(1987), the compound (V) may also be prepared by the following reaction scheme B. ##STR3##
Both the above two processes for preparing compounds (V) were carried out in anhydrous condition at lower temperature with the introduction of inert gas, and involved the use of alkali metal salts of secondary amine. Accordingly, the preparation of compounds (V) according to the above mentioned processes require critical anhydrous reaction conditions with complicated procedures and apparatus in production scale. Moreover, the hazardous alkali metal salts must be handled with care and therefore are not suitable for scaling up production in industry.